Platinum alloy



Patented Feb. 17, 1942 UNITED STATES PATENT OFFICE 2,273,805 PLATINUMALLOY .Edmund Merriman Wise, Westfield, and Raymond Francis Vines,Garwood, N. J., assignors to The International Nickel Company, Inc., NewYork, N. Y., a corporation of Delaware No Drawing. Application April-24,1941, Serial No. 300,104. In Canada March 22, 1941 3 Claims.

' than was platinum. In addition, with the usual iridium contents ofabout 5% to the alloys were not very hard in the cast or fully annealedconditions and also had a higher density than platinum. Theruthenium-platinum and osmiumplatinum alloys, especially thosecontaining more than about 5% of ruthenium or osmium, gave ofi poisonousfumes during melting had a higher melting point than platinum and didnot have very good ductility.

Because of the disadvantages of the higher ruthenium and. osmium contentalloys, the art has been limited essentially to the iridiumplatinum.alloys for applications where increased hardness was required. However,as pointed out hereinbefore, the iridium-platinum alloys were costly,had a high melting point and were difficult to cast in the usualinvestments. The art has been constantly seeking to overcome these andother disadvantages and although many attempts were made to remedy theaforementioned shortcomings,.none, as far as we are aware, was entirelysuccessful when carried into practice commercially.

We have discovered that the prior art shortcomings can be avoided andthat new and unexpected results canbe obtained by using small controlledamounts of tin as a hardener in platinum and platinum base alloys. Wehave discovered that platinum-tin alloys possess improved hardnesseswithout loss of ductility, have lower melting points, and are easier tocast than the platinum-iridium alloys commonly used heretofore.

balance substantially all platinum.

lower in cost, while retaining good ductility, than the iridium-platinumalloy of similar hardness.

The present invention contemplates new hard platinum alloys for jewelrypurposes, dental purposes, etc., which do not require the use of therare and costly element iridium.

The invention also contemplates dental structures and jewelry and otherarticles of manufacture made of the alloys provided by the presentinvention.

Other objects and advantages of the invention will become apparentfrom'the following description.

The invention provides improved platinumbase alloys containing small buteffective amounts of tin, say about 0.35% to about 5%, and the Inaddition to tin and platinum, the alloys may, contain small amounts lessthan about 5% of base metals, e. g., copper, nickel, molybdenum,tungsten, etc. The base metals may be present as minor constituentswhich improve certain other desired properties. Thus, the presentinvention includes platinum-copper-tin alloys containing .tin andplatinum in the amounts herein set forth and about 4% copper.

The tin-containing platinum alloys provided by the present invention donot contain over about 5% tin, preferably not more than 3% tin for bestductility. Tin contents in excess of about 5% appear to detrimentallyaffect the working propertiesand to cause cr'acking'upon rolling, etc.Contrary to the belief that tin is detrimental in platinum and highplatinum alloys due' to its embrittling'efiect, we have made theastonishing discovery that platinum and high platinum alloys containingup to about 3% tin are ductile and exhibit satisfactory workingproperties. In general, it is pneferred to maintain the tin contenttoward the minimum values, for example, about 0.5%, for-alloys to befabricated into intricate design. A particularly suitable alloy forfabrication into intricate designs contains about 0.5% tin and thebalance substantially all platinum. A study of platinum alloyscontaining up to about 3% tin has revealed that such alloys apparentlydid not age harden andthat the markedly in- It is anobject of thepresent invention to proa lower melting point, is easier to cast, and iscreased hardness of the tin-containing alloys was not due to an agehardening effect. Some age hardening effects were observed in a 95/5platinum-tin alloy. 1

The tin-containing platinum-base alloys of the present invention arecharacterized by improved hardnesses of at least about Vickers hardnessnumber.

The improved hardening effects of tin as contemplated herein areobtained in alloys containing a small but effective amount of tin, sayabout 0.35%, to about 5% tin, and the balance platinum, i. e., about 95%to 99.65% platinum. Preferably, the alloys contain at least about 0.45or 0.5% tin and up to about 3% tin where maximum ductility is desired.Wehave found that small amounts of tin have much greater hardeningefiect than the same amount of known hardening agents for platinum suchas iridium, ruthenium, osmium, rhodium, gold, silver, nickel, copper,iron, etc. The beneficial and improved effects of tin compared toiridium in platinum alloys are illustrated in Table I which sets forththe comparative hardnesses in the fully annealed condition and theapproximate melting points of tin-platinum, and iridium-platinum alloys,as well as of substantially pure platinum.

Table I Melting Composition Point Pure platinum V. H. N.=Vickershardness number (10 kg. load) after 50% cold reduction followed byannealing at 1,l C. for 30 minutes and Water quenching.

over from the ore, incorporated during process- 7 ing, etc. Some of thepurer grades of commercially available platinum may contain only about0.001% or 0.01% of other platinum group metals while less pure gradesmay contain more. As will be apparent to those skilled in the art, theincidental elements and impurities contained in platarticle.

Alloys Nos. 5, 6 and 7 which were made in accordance with the presentinvention show marked increases in hardness, while retaining good duc-Alloys No. 6 and No.-7 which contained about 3% and about tin,respectively, possessedhigher hardnesses than alloys No. 2 and No. 3which contained 10% and iridium, respectively.

The accompanying beneficial eifect of tin com- I pared to iridium inlowering the melting point while increasing the hardness is clearlyillustrated in Table I.

In addition to platinum and tin, the alloys of the present invention maycontain small amounts of incidental or minor constituents and impuritiesand when we state that platinum constitutes the balance or that thebalance is substantially all platinum we do not intend to exclude smallamounts of incidental or minor constituents and impurities. smallamounts of base metals, for example, copper, nickel, molybdenum,tungsten, etc., in small I amounts more than 0.01% and less than 5%.

Likewise, the platinum-base alloys may contain I small amounts of otherknown non-platinum' group metal hardeners of platinum to supplement thebeneficial effects of tin. Furthermore, the alloys may contain smallamounts of iron, magnesium, calcium and other elements com- Thus, thalloys may contain inum may be carried over into-thefinal alloy or Itisto be understood that when it is stated that the balance is platinumor substantially all platinum, we do not exclude from the scope of theexpression incidental and minor constituents and impurities which may bepresent in such amounts as occur in commercially available platinum andin commercially produced platinum products, or in amounts not adverselyaffecting the desired properties of the platinumbase alloy.

The present invention provides hard articles of manufacture made of theplatinum alloys described hereinbefore and containing small buteflective amounts of tin, for example, alloys containing about 0.35% toabout 5% tin and the balance substantially all platinum, said platinumalloys possessing improved castability when molten and improved hardnessin the solid state while retaining goodductility. The articlescontemplated herein may be made of cast or wrought alloys. Anillustrative example of a suitable wrought alloy for the manufacture ofarticles where high platinum group metal content and good workabilitycombined with adequate hardness is required contains 0.5% tin andbalance substantially all platinum. Larger amounts of tin may be usedwhere high purity. is not a primary factor but where good ductility isdesired it is preferred that the tin content not exceed about 3%. Anillustrative example of a cast alloy and casting suitable for articleswhere high hardness combined with adequate ductility are primary factorsand where highest purity is not essential contains 1% to 3% tin and thebalance substantially all platinum.

Illustrative examples of wrought and/or cast articles within the scopeof the present invention include 'cast and wrought dental structures,restorations and the like, for example, cast dental restorations, suchas bridges, inlays, crowns, abutments, etc.; cast and wrought jewelry,for

example rings, chains, brooches, clips, pins,,

parting from the spirit and scope of the invention, as those skilled inthe artwill readily understand. Such variations and modificationsapparent to those skilled in the art are considered to be within thepurview and scope of the ap- 0.35% to about 3% tin and the balancesubstan pended claims. tially all platinum.

We claim: 3. A workable platinum alloy comprising about 1. A platinumalloy comprising a small but 0.5% tin and the balance substantially alleffective amount up to about 5% of tin and the 5 platinum.

balance substantially all platinum. EDMUND MERRIMAN WISE.

"2. A workable platinum alloy comprising about RAYMOND FRANCIS VINES.

